The recent tendency in designing furniture and architecture is that curved surfaces are positively employed in various parts from the viewpoint of design and function. Works produced from such a viewpoint are for example desks and tables having curved front panels, doors and partition walls the whole face plates of which are curved, arched ceilings having curved interior surfaces, and pillars circumferentially covered with a decorative hollow cylindrical member.
The front panels, face plates, interior surfaces and decorative members of the above-mentioned types are usually made of steel plate by pressing. For pressing such material those dies which conform to the desired shapes of the products are required. If the abovementioned relatively large-sized panel is to be formed by this method, the die must be as large as the panel to be formed and becomes expensive. As many dies as there are various kinds of products are required, with resulting increase in the manufacturing cost. Large-sized dies would necessarily require a large-sized machine. Since pressing utilizes plastic deformation, a strain is left in the pressed part after the exterior force has been removed. Therefore, the larger the curved surface is, the higher degree of precision is required for pressing. Otherwise, an unnecessarily large strain would be left in the pressed workpiece, so that it would become difficult to produce a good curved surface in the finished product.
In view of the above problems, this invention has been made, its object being to provide a curved panel which has various advantages such that it is possible to reduce the size of the apparatus, easily produce products of various specifications, reduce the manufacturing cost and improve the quality of the finished curved surface.